It's a redevelopment so big that many who first learned of it last week said they were overwhelmed by what's expected to replace Seattle's Yesler Terrace and its 561 units of public housing: 3,000 to 5,000 high-rise apartments and condos and up to 1.5 million square feet of office space.

"This is shocking. These are big numbers," said Mark Okazaki, director of Seattle's nonprofit Neighborhood House and a member of the Yesler Terrace Citizens Review Committee that met last week.

Today's low-income apartments, most of which occupy two-story buildings on 28 acres overlooking downtown Seattle, were built in 1939 and have failing plumbing, says Yesler Terrace's owner, the Seattle Housing Authority. In 2007, the agency convened a citizens committee that set guidelines for turning the site into a public-private mixed-income community similar to what SHA has done in South Seattle at NewHolly, High Point, and Rainier Vista.

Unlike those redevelopments, however, the agency will have no federal HOPE VI grant money this time around and says it must raise all the capital itself to replace the low-income units. On Dec. 10, at the second public meeting of a new citizens committee called to look at concept plans for Yesler Terrace, the housing authority said it will raise the money by redeveloping the site for residential towers of 3,000 to 5,000 units, one or more office towers of 800,000 to 1.2 million square feet and up to 100,000 square feet of retail space.

In a written statement issued the same day, the housing authority gave different figures, saying the redevelopment would include up to 250,000 square feet of retail space and 1.5 million square feet of office space -- the rough equivalent of five full-size grocery stores and one Columbia Center-size office tower, with SHA expecting medical providers to lease the more lucrative office space it plans to the site's north, near Harborview Medical Center.

The agency says selling some of Yesler Terrace for private condos, homes, and offices is the only way it can pay for replacing the site's low-income units, which SHA project manager Judith Kilgore told committee members last week will cost $120 million to $140 million out of a total project cost she estimated at $240 million to $307 million.

The cost, she and SHA consultant Tom Hudson said, reflects a green-minded development that will be family- and senior-friendly and include a number of amenities requested by tenants such as apartments with full-size balconies, a central plaza for community events, and five to eight blocks of pocket parks, playgrounds, and open space for residents to garden and grow food.

"We are still operating under the premise that Yesler Terrace pays for itself. Right now, we're looking at building it completely on our own," Kilgore said after giving the redevelopment figures.

Committee members expressed surprise at the scale of the redevelopment.

"I'm a bit overwhelmed and have a lot of questions," said John Fox of the Seattle Displacement Coalition.

"I, too, feel a little overwhelmed in terms of what's been shared about the density," said fellow committee member Kent Koth, director of Seattle University's Center for Service and Community Engagement.

"I'm looking at the price tag and it's just shocking," Okazaki said. "Are there other options? Are there any alternatives to squeeze out another 10 years [at Yesler Terrace]?" he asked.

What's missing, said committee chair Germaine Covington, former director of the Seattle Office for Civil Rights, are numbers comparing renovating the infrastructure at Yesler Terrace versus rebuilding the whole site.

"We can give you a number, but there's no funding source," said Al Levine, the housing authority's deputy director. He added that it was "apples and oranges" to compare a no-budget renovation of Yesler Terrace's low-income housing units with a development that will pay for new ones. "The replacement housing will cost $140 million," he said. "That's no small change."

But Fox said the agency is drifting from its mission to house the poorest of Seattle's poor. "With this project," he added after the meeting, "SHA essentially becomes a high-rise office developer and major player in the downtown office scene."

The committee's next meeting is scheduled for Jan. 15, when the housing authority plans to present "concepts" and visuals for a denser Yesler Terrace. The group has four more meetings scheduled through April to pick a concept, which SHA consultants will then develop into site alternatives for presentation to the housing authority's Board of Commissioners for a final decision.

The housing authority says it expects to start an environment impact study at Yesler Terrace next summer and break ground no earlier than 2011.